The Contractor shall perform in vivo and in vitro quantitative comparisons of the lethal effects of alternative therapies on tumor cells and hematopoetic stemm cells. More specifically, the Contractor shall: Determine dose and time survival curves for anticancer agents specified and supplied by the NCI Project Officer for normal bone marrow and several murine tumors; Determine the tumor cytosidal and host toxicity characteristics of specific two drug combinations or combinations of drug and radiotherapy; and Make recommendations regarding principles of drug sequence and dose intervals based on evaluation of these results and the results of in vivo therapeutic data, as available from the National Cancer Institute.